Bach: WTC I, Prelude and Fugue in E minor

The Prelude and Fugue in E minor are two of my favorite pieces from the Well-Tempered Clavier, especially the prelude. It is an odd sort of hybrid piece with an opening ornamented aria for soprano over an obbligato bass followed by a toccata. Oddly, it is not the soprano melody that sticks in your head, but that obbligato bass line:

When the presto finally arrives it is devoted to that same obbligato transposed up a fourth:

The fugue subject, to my mind, bears something of a family resemblance to that same theme, but chromatically altered:

That's not quite a twelve-tone theme (though I believe there is one in the Well-Tempered Clavier somewhere) as it is missing A natural and F natural, but it has all the other notes. Most fugue subjects start with tonic harmony and move to dominant harmony, but usually not as strongly as this does. The effect of the A#s is to strongly tonicize B, but then we end up on a D natural, so B minor is suggested. The second entry of the subject takes us to B's dominant of F#. After an episode, we have the subject in G. In every instance, except the first, the subject is accompanied by its countersubject:

And when I say "in every instance, except the first" I mean it. We even get the countersubject without the subject a couple of times. The episodes are also important with crossing sequences, by which I mean that the material in one voice crosses to the other as the material is repeated at a different interval. There is a heck of a lot going on in this fugue which is, in Glenn Gould's performance, less than a minute long.

Speaking of tempo, I feel that most performances of the prelude are a bit too fast, with not enough contrast with the presto. And some performances of the fugue are not quite fast enough. In this case I think Gould has the tempos exactly right. Here are his performances. Sorry, I couldn't find the fugue to embed so you will have to follow the link.

https://www.youtube.com/watch?v=GJ5rZQr-qTk